I don't speak or write Japanese, but I know how to read the letters. With the help of web translation, here's some info I've been able to gather. Some of it might not be accurate though, due to my faulty understanding.

Discontinued support for RIFF SIF tags.Although playback of RIFF SIF data is possible, tag is no longer read.

Ver. 1.18y ot105.1Changed search order of mp3infp.dll.

Ver. 1.18y ot104.4

When saving streams to files, doesn't overwrite existing files.

When saving streams to files, doesn't save if server is down.

Ver. 1.18y ot103

Hands exact playback position to visualization plugins.

Fixed crashes that occurred when using DSP plugins.

Ver. 1.18y ot102Fixed noise bug with some input data.

Ver. 1.18y ot101.2

Changed installation method.Changed installation method if Winamp is installed on an NTFS filesystem. For details, please consult the installation documents.

Changed filename to in_!mpg123.dll. (To make Winamp recognize it before in_mp3.dll on NTFS.)

Fixed bug where streaming playback couldn't be disabled with newer versions of Winamp.It is unclear since which version of Winamp that it couldn't be disabled, so the fix is in effect for Winamp 5.11 and higher.

Ver. 1.18y ot99.1All calculations are now based on 64bit float values until right before data output.Reverse stereo, invert phase, and volume calculations are all in 64bit float too. It's converted to the target format just before data output.

Ver. 1.18y ot98Speeded up conversion of float to int when handing data to visualization plugins.

Ver. 1.18y ot97.1

Changed the method playback starts.

Changed the method of synchronization between threads.

Removed requirement of Winamp 5.12 or newer.Works with versions older than Winamp 5.12.

Ver. 1.18y ot96.1Fixed lockups happening when playback was started in quick succession.

Ver. 1.18y ot62Fixed problem of Winamp behaving strangely with long title formatting strings if Advanced Title Formatting was not used.

Ver. 1.18y ot61c

Supports Replay Gain.Replay Gain info is read from ID3v2, APE and LAME tags. The reading order is ID3v2 -> APE -> LAME.Please use foobar2000 when writing Replay Gain info to ID3v2 or APE tags. (Reading of Replay Gain data written in ID3v2 or APE tags is compatible with that of foobar2000.)When writing Replay Gain data in LAME tags, please use LAME 3.95 or above to encode.Please refer to http://replaygain.hydrogenaudio.org/ for in-depth information on Replay Gain.

Fixed problem with line-final characters not being read if Unicode is used with ID3v2.

Ver. 1.18y ot60bFixed pause/seeking not working immediately after start of playback.